Liquid consuming apparatus with a movable holder having an inclined face

ABSTRACT

The liquid consuming apparatus includes a detection portion  90  having a light-emitting portion  92  and a light-receiving portion  94 , a holder  20  in which a liquid container provided with a prism  170  is attachably and detachably installed, the holder  20  having an opening portion  22  provided at a position facing the prism  170  when the liquid container is installed, and a reflection portion  24 , and a moving portion that relatively moves the holder in a first direction with respect to the detection portion  90 . A first portion of the holder  20  that is peripheral to the reflection portion  24  in a plan view of the holder  20  as seen from the side of the detection portion  90  has an inclined face that inclines in a second direction intersecting the first direction.

BACKGROUND

1. Technical Field

The present invention relates to a liquid consuming apparatus or thelike.

2. Related Art

In an inkjet printer serving as an exemplary liquid consuming apparatus,in general, an ink cartridge, which is a detachable liquid container, isinstalled. A printer is disclosed that includes an ink cartridgeprovided with a prism, a holder (carriage) in which the ink cartridge isinstalled and that is provided with an opening portion at a positionfacing the prism, and a detection portion having a light-emittingportion and a light-receiving portion, in order to detect the amount ofremaining ink in the ink cartridge (e.g., see JP-A-2013-99890).

When the light radiated by the light-emitting portion and entering fromthe opening portion of the holder is reflected at an inclined face ofthe prism, the state of reflection differs depending on whether or notthe inclined face is in contact with the ink. Using this fact, theamount of remaining ink is detected based on the level of intensity orthe like of the reflected light that enters the light-receiving portion.For this reason, for example, the reflected light that is reflected atthe holder, a bottom face of the prism, or the like could be noise lightand be a factor that hinders accurate detection of the amount ofremaining ink in some cases.

In the printer described in JP-A-2013-99890, a light-blocking portion isprovided in the opening portion of the holder. When the holder moves ina direction in which the light-emitting portion and the light-receivingportion are arranged, a part of the light radiated from thelight-emitting portion is blocked by the light-blocking portion, therebysuppressing reflection at the bottom face of the prism. Furthermore, thelight entering the light-blocking portion is caused to be reflected in adirection other than the direction toward the light-receiving portion byforming the bottom face (a face facing the detection portion) of thelight-blocking portion into an inclined face inclining in the directionin which the light-emitting portion and the light-receiving portion arearranged. Thus, reduction of the noise light is achieved.

Incidentally, the amount of remaining ink is detected when relativepositions of the prism and the detection portion reach a predeterminedposition (hereinafter referred to also as a detection position).However, the detection position is shifted from an originally-assumeddetection position in some cases. For this reason, for example, areflection portion is provided in the holder. Before the amount ofremaining ink is detected, the holder is relatively moved with respectto the detection portion, the position of the reflection portion isdetected based on the intensity level or the like of reflected lightreceived by a light-receiving portion, and further, the detectionposition is corrected.

However, position correction processing using the reflection portion isperformed by detecting, using the light-receiving portion, the reflectedlight that is emitted from a light-emitting portion in the detectionportion and reflected at this reflection portion. For this reason, ifother light is received by the light-receiving portion, the accuracy ofthe position correction processing will decrease. “Other light”mentioned here is, for example, ambient light that enters from theoutside of the liquid consuming apparatus and light that is emitted fromthe light-emitting portion and reflected at a portion other than thereflection portion (e.g., reflected at the bottom face of the holder).

SUMMARY

According to some aspects of the invention, a liquid consuming apparatusor the like can be provided that performs accurate position correctionprocessing, as a result of providing an inclined face in an areaperipheral to a reflection portion of a holder.

An aspect of the invention relates to a liquid consuming apparatusincluding: a detection portion having a light-emitting portion and alight-receiving portion; a holder in which a liquid container providedwith a prism is attachably and detachably installed, the holder havingan opening portion provided at a position facing the prism when theliquid container is installed, and a reflection portion; and a movingportion that relatively moves the holder in a first direction withrespect to the detection portion. In the liquid consuming apparatus, afirst portion of the holder that is peripheral to the reflection portionin a plan view of the holder as seen from the side of the detectionportion has an inclined face that inclines in a second directionintersecting the first direction.

In an aspect of the invention, the inclined face is provided in thefirst portion peripheral to the reflection portion of the holder, theinclined face inclining in the second direction intersecting the firstdirection that is the relative moving direction of the holder and thedetection portion. For this reason, it is possible to suppress ambientlight or reflected light at the holder entering the light-receivingportion and a detected waveform becoming asymmetric, and to accuratelyperform position correction processing and the like.

In an aspect of the invention, the first portion may have a plurality ofsteps of inclined faces that incline in the second direction.

With this configuration, the influence of ambient light can be furthersuppressed by providing the plurality of inclined faces.

In an aspect of the invention, the first portion may have a first to Nth(N is an integer larger than or equal to 2) inclined faces arranged inthe second direction, and the distance between the detection portion andthe holder at an end point of an ith (i is an integer that satisfies1≦i<N) inclined face on the side of an i+1th inclined face may be largerthan the distance between the detection portion and the holder at an endpoint of the i+1th inclined face on the side of the ith inclined face.

With this configuration, the distance between the detection portion andthe holder can be reduced, and the influence of ambient light can befurther suppressed.

In an aspect of the invention, a control portion may be further includedthat performs processing for correcting a positional relationshipbetween the holder and the detection portion when determining the amountof remaining liquid, based on a detection signal from the detectionportion indicating a light reception result of reflected light at thereflection portion.

With this configuration, position correction processing can be performedusing the reflected light at the reflection portion.

In an aspect of the invention, a plurality of the liquid containers maybe able to be attached to and detached from the holder, the holder maybe able to hold the liquid containers, and the holder may have aplurality of the opening portions that are each provided at a positionfacing each of a plurality of the prisms when the liquid containers areinstalled. The first portion may be a portion between the reflectionportion and a first opening portion among the opening portions.

With this configuration, the inclined face inclining in the seconddirection can be provided in the portion between the reflection portionand the opening portion.

In an aspect of the invention, a plurality of the liquid containers maybe able to be attached to and detached from the holder, the holder maybe able to hold the liquid containers, and the holder may have aplurality of the opening portions that are each provided at a positionfacing each of a plurality of the prisms when the liquid containers areinstalled. The first portion may be a portion on the side opposite to afirst opening portion among the opening portions with respect to thereflection portion.

With this configuration, the inclined face inclining in the seconddirection can be provided in the portion on the side opposite to theopening portion with respect to the reflection portion.

In an aspect to the invention, a portion between two adjacent openingportions among the opening portions may have an inclined face thatinclines in the first direction.

With this configuration, as a result of providing the inclined facebetween the opening portions, it is possible to accurately determine theamount of remaining liquid or the like.

In an aspect of the invention, a first liquid container and a secondliquid container whose capacity is smaller than that of the first liquidcontainer may be able to be attached to and detached from the holder,and the holder may be able to hold the first liquid container and thesecond liquid container. The reflection portion of the holder may beprovided in the holder on the side of the second liquid container.

With this configuration, as a result of separately providing the firstliquid container and the reflection portion, it is possible toefficiently suppress the influence of ambient light or the like indetermination of the amount of remaining ink or the like.

In an aspect of the invention, the second direction may be a directionorthogonal to the first direction.

With this configuration, the direction of providing the inclined facecan be set as the direction orthogonal to the first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C show exemplary shapes of a holder bottom face peripheralto a reflection portion.

FIGS. 2A to 2C show results of simulation of a detection signal obtainedwith the respective shapes of the holder bottom face.

FIGS. 3A and 3B show an exemplary configuration of a holder according tothe present embodiment.

FIG. 4 is a perspective view showing a main part of a printer accordingto the present embodiment.

FIG. 5 is a schematic block diagram of the printer according to thepresent embodiment.

FIG. 6 is an illustrative diagram showing an electric configuration of adetection portion.

FIG. 7 shows another exemplary configuration of a light-receivingportion.

FIG. 8 is a perspective view of an ink cartridge.

FIGS. 9A and 9B are diagrams illustrating a detailed configuration ofthe holder according to the present embodiment.

FIG. 10 is a diagram for illustrating a state of reflected light whenlight is radiated from a light-emitting portion.

FIG. 11 shows an example in which the holder has a plurality of inclinedfaces.

FIGS. 12A and 12B are diagrams illustrating a difference between aholder having an inclined face and a holder having a plurality ofinclined faces.

FIGS. 13A and 13B are diagrams illustrating an ink near-enddetermination method.

FIGS. 14A and 13B are diagrams illustrating an ink near-enddetermination method.

FIG. 15 is a flowchart showing ink near-end determination processing.

FIG. 16 is a flowchart showing the details of prism position correctionprocessing.

FIG. 17 is a diagram for illustrating a state of reflected light oflight radiated from the light-emitting portion, with regard to thereflection portion and the ink cartridge.

FIG. 18 is a diagram showing an exemplary result of measurement ofoutput voltage from the detection portion with respect to each state ofreflected light.

FIGS. 19A and 19B are diagrams illustrating a detailed configuration ofthe holder according to the present embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present embodiment will be described. Note that thepresent embodiment described below is not intended to unjustly limit thecontent of the invention described in the scope of claims. Not allconfigurations described in the present embodiment are necessarilyessential constituent elements of the invention.

1. TECHNIQUE IN PRESENT EMBODIMENT

First, a technique in the present embodiment will be described. Asmentioned above, desired light needs to be detected by a detectionportion in position correction processing, and signal componentsgenerated due to light other than the desired light will be noise thathinders the processing. Specifically, since reflected light at areflection portion 24 is used in processing as described later usingFIGS. 17 and 18, it is conceivable that ambient light and reflectedlight at a bottom face 21 (a face facing a detection portion 90) of aholder 20 are noise factors.

Firstly, in order to suppress the reflected light at the holder bottomface 21, a technique of realizing this holder bottom face 21 by using anon-reflective member is conceivable. However, even if a non-reflectivemember is used, the reflected light cannot be reduced to zero, and thereis a possibility that noise occurs.

FIGS. 1A to 1C show various shapes of the holder bottom face 21(specifically, shapes of a reflection portion and a peripheral portionof the holder), and FIGS. 2A to 2C show results of simulation ofdetection signals at a light-receiving portion when using the holderbottom face of the respective shapes. FIG. 2A shows a simulation resultcorresponding to the holder bottom face in FIG. 1A. Similarly, FIGS. 2Band 2C correspond to FIGS. 1B and 1C, respectively. As described laterusing FIG. 4, the Y-axis indicates a main scanning direction HDcorresponding to the relative moving direction of the holder and adetection portion, and the X-axis indicates a sub-scanning direction VD.The Z-axis is an axis orthogonal to the Y-axis and the X-axis, and is avertically upward direction when in a normal use state.

Note that the holder 20 here has a recess portion 26, and the reflectionportion 24 is provided in this recess portion 26. Since the bottom face21 of the holder 20 is a face facing the detection portion 90 asmentioned above, a plurality of faces are included in the bottom face 21in the holder 20 having such a shape. For example, a face 21 a includinga point A1 and a face 21 b having a point B1 in FIG. 1A are included inthe bottom face 21 of the holder 20. The bottom face 21 is not limitedthereto, and a bottom face 21 c of the recess portion 26 in which thereflection portion 24 is provided is also included in the bottom face 21of the holder 20. Note that, in FIG. 1B and subsequent drawings, thesame reference numeral (21) will be given to all of the plurality offaces included in the bottom face 21 of the holder 20, unless otherwisestated.

Here, it is assumed that the light-emitting portion ideally emits light,and laser light is used in the simulation. Even if a non-reflectivemember is used as the holder bottom face 21, if this bottom face 21 isarranged substantially parallel with the face in which thelight-emitting portion 92 and the light-receiving portion 94 arearranged as shown in FIG. 1C, the influence of the reflected light atthe holder bottom face 21 cannot be sufficiently suppressed.Specifically, in a range smaller than or equal to −1 on the horizontalaxis in FIG. 2C, a signal is detected that causes noise in the positioncorrection processing. Note that the horizontal axes in FIGS. 2A to 2Ccorrespond to the main scanning direction (Y-axis), and the verticalaxes correspond to the signal intensity. The origin (0) of thehorizontal axis indicates a relative positional relationship in whichthe center position between the light-emitting portion and thelight-receiving portion coincides with the center position of thereflection portion (reflecting plate) in the main scanning direction.

In contrast, the influence of the reflected light at the holder bottomface 21 can be suppressed by providing an inclined face in the holderbottom face 21. For example, when employing the shape of the holder 20shown in FIG. 1A, the bottom face has inclined faces inclining in themain scanning direction (Y-axis direction) (i.e., faces whose distancein the Z-axis direction from the face in which the light-receivingportion and the light-emitting portion are arranged monotonouslyincreases or decreases along the Y-axis). For this reason, light L1 aemitted from the light-emitting portion 92 is reflected at the holderbottom face 21 in the direction indicated in FIG. 1A, and is unlikely tobe detected by the light-receiving portion 94. As a result, theinfluence of noise caused by the reflected light at the holder bottomface 21 can be suppressed as shown in FIG. 2A.

However, as can be found by comparing the points A1 and B1 in FIG. 1A,the height of the holder 20 (i.e., the length thereof in the Z-axisdirection relative to the reflection portion) differs in the +Ydirection and the −Y direction of the reflection portion. For example,when assuming the height as the distance in the Z-axis direction from areference point, which is on the surface of the reflection portion 24,the heights of the points A1 and B1 are HA1 and HB1, respectively, asshown in FIG. 1A. In the case of FIG. 1A, HA1<H1B.

For this reason, in the +Y direction, the light that is radiated fromthe light-emitting portion 92, reflected at the reflection portion 24,and received by the light-receiving portion 94 is blocked at the pointA1, and a position YA1 is the boundary in the main scanning directionthat determines whether or not the reflected light from the reflectionportion 24 can be detected by the light-receiving portion 94. In otherwords, if the position at which light is reflected at the reflectionportion 24 moves from YA1 further in the +y direction, the reflectedlight is blocked by the holder 20 (particularly, a face in an XZ planeincluding the point A1) and cannot be received by the light-receivingportion 94.

Meanwhile, in the −y direction, since the aforementioned light isblocked at B1 that is higher than A1, the boundary in the main scanningdirection that determines whether or not the light can be detected isconsidered to be a position YB1. Due to the difference in the heightbetween A1 and B1, the distance from the center position of thereflection portion 24 to YB1 is smaller than the distance from thecenter portion of the reflection portion 24 to YA1.

Consequently, the detection signal corresponding to FIG. 1A has anasymmetric shape with respect to the origin of the horizontal axis, asshown in FIG. 2A. Since position correction is performed by finding peakpositions as described later using FIG. 18, the center position of thereflection portion 24 cannot be appropriately determined if the signalin FIG. 2A is used.

In contrast, a technique is conceivable of resolving an asymmetricdetection signal by making the height of the holder 20 uniform in the +Ydirection and the −Y direction, as shown in FIG. 1B. With the shape inFIG. 1B, since the heights of points A2 and B2 relative to thereflection portion 24 are equal (HA2=HB2), the distances from the centerposition of the reflection portion 24 to YA2 and YB2 are equal. As aresult, a left-right symmetric signal waveform is obtained as shown inFIG. 2B, and accordingly the center position of the reflection portion24 can be detected.

However, ambient light is not considered in the simulation in FIG. 2B.For example, when the cover of the printer is open, light from theoutside such as sunlight or illumination light enters, as ambient light,the inside of the apparatus. This ambient light is, of course, lightthat is not assumed to be detected in the processing, and thereforebecomes noise that reduces the processing accuracy. In the shape in FIG.1B, the height of the holder bottom face 21 in the −Y direction is lowerthan in FIG. 1A in order to make the heights of the points A2 and B2uniform. For this reason, depending on the position at which thereflection portion of the holder is arranged, there is a possibilitythat ambient light denoted by L2 a in FIG. 1B enters the light-receivingportion.

That is to say, the shape in FIG. 1B cannot be considered to bepreferable either, in terms of suppression of the influence of ambientlight. For the above-described reason, the present inventor proposes atechnique of providing, in the holder bottom face 21, an inclined faceinclining in a direction intersecting the main scanning direction.Specifically, as shown in FIG. 4, a liquid consuming apparatus accordingto the present embodiment includes a detection portion 90 having alight-emitting portion 92 and a light-receiving portion 94, a holder 20in which liquid containers (corresponding to ink cartridges IC) eachprovided with a prism (a prism 170 in FIG. 8) are attachably anddetachably installed, the holder 20 having a reflection portion 24 andopening portions 22 provided at positions facing the prisms when theliquid containers are installed, and a moving portion (corresponding toa carriage motor 33) that relatively moves the holder 20 in a firstdirection with respect to the detection portion 90. A first portion(e.g., a portion indicated by oblique lines in FIG. 9A) of the holder 20that is peripheral to the reflection portion 24 in a plan view of theholder 20 as seen from the side of the detection portion 90 has inclinedfaces that incline in a second direction intersecting the firstdirection.

Specifically, the second direction may be a direction orthogonal to thefirst direction, and assuming that the first direction is the mainscanning direction HD (Y-axis), the second direction is the sub-scanningdirection VD (X-axis). In this case, the shape of the holder 20peripheral to the reflection portion 24 is as shown in FIGS. 3A and 3B.FIG. 3A shows the shape of the holder 20 in an XZ plane, and FIG. 3Bshows the shape of the holder 20 in a YZ plane.

Here, an inclined face that inclines in a predetermined direction refersto a face whose position in a direction intersecting the predetermineddirection monotonously increases or monotonously decreases when theposition in the predetermined direction constantly changes. In theexample in FIG. 3A, the inclined face is a face whose the position in athird direction (Z-axis) intersecting the second direction monotonouslychanges from the +Z direction toward the −Z direction, in the positivedirection of the second direction (X-axis).

With this configuration, it is possible to provide the inclined faces inthe bottom face 21 of the holder 20 while causing the heights thereofrelative to the reflection portion, i.e., the Z-axis coordinate valuesthereof to correspond to each other (narrowly defined, to be the same)on one side and the other side in the Y-axis direction with respect tothe reflection portion 24. That is to say, two portions of the holderbottom face peripheral to the reflection portion in the Y-axis directionare provided with inclined faces that incline in the X-axis direction soas to be aligned with the same direction, and accordingly, the height ofthe recess portion from the reflection portion to the holder bottom facecan be made uniform. For example, assuming that a Z-axis coordinatevalue of the holder bottom face 21 at a position facing thelight-emitting portion 92 and the light-receiving portion 94 of thedetection portion 90 is z1, as shown in FIG. 3A, both Z-axis coordinatevalues of the points A and B in the YZ plane including thelight-emitting portion 92 and the light-receiving portion 94 are z1, asshown in FIG. 3B. Since the holder 20 thereby have the inclined faces,the influence of reflected light due to the holder 20 can be suppressedin the position correction processing, unlike in the example in FIG. 1C.Also, since the heights of the points A and B are equal to each other,the detection signal do not become asymmetric with respect to the centerof the reflection portion 24 in the Y-axis direction, unlike in theexample in FIG. 1A. That is to say, with the liquid consuming apparatusin the present embodiment, the position correction processing can beaccurately executed.

Hereinafter, a liquid consuming apparatus in the present embodiment willbe described in detail. A basic configuration of the liquid consumingapparatus and an exemplary configuration of the ink cartridges will bedescribed first, and subsequently an exemplary configuration of theholder will be described. Furthermore, a description will be given of atechnique of determining the amount of remaining liquid (ink near-enddetection technique) and a position correction technique, and lastly ofmodifications.

2. BASIC CONFIGURATION OF PRINTER, INK CARTRIDGES

A basic configuration of a printer serving as a liquid consumingapparatus according to the present embodiment will be described withreference to FIGS. 4 and 5. FIG. 4 is a perspective view showing a mainpart of the printer according to the present embodiment. FIG. 5 is aschematic block diagram of the printer according to the presentembodiment.

FIG. 4 shows a Y-axis direction serving as a first direction, an X-axisdirection that is perpendicular to the Y-axis direction and serves as asecond direction, and a Z-axis direction that is perpendicular to theX-axis direction and the Y-axis direction and serves as the thirddirection. In the present embodiment, in the posture of a printer 10when in use, the Z-axis direction (+Z direction and −Z direction) is thevertical direction, and a +X direction is the direction toward the frontof the printer 10. The Y-axis direction (+Y direction and −Y direction)is a main scanning direction HD of the printer 10, and the X-axisdirection (+X direction and −X direction) is a sub-scanning direction VDof the printer 10.

As shown in FIG. 4, the printer 10 includes a plurality of inkcartridges IC each serving as a liquid containing portion, a carriage CRincluding a holder 20, a paper feed motor 30, a carriage motor 33serving as a moving portion, a cable FFC1, a detection portion 90, and acontrol unit 40. For example, cyan ink, magenta ink, yellow ink, andblack ink are contained in the respective ink cartridges IC. The inkcartridges IC are installed in the holder 20. Note that the holder 20may be formed as a member integrated with the carriage CR, or may beformed as a separate member and incorporated in the carriage CR.

As shown in FIG. 5, the carriage CR includes the holder 20 and a printhead 35. The carriage CR moves back and forth above a print medium PA inthe main scanning direction HD, by being driven by the carriage motor33. The paper feed motor 30 conveys the print medium PA in thesub-scanning direction VD. The print head 35 is carried in the carriageCR, and discharges ink supplied from the ink cartridges IC. Note that,in FIGS. 4 and 5, the carriage CR is located at its home position.

The detection portion 90 outputs a signal for detecting the amount ofremaining ink in the ink cartridges IC to the control unit 40. Thedetection portion 90 includes a light-emitting portion 92(light-emitting device) that radiates light toward a prism 170 (see FIG.8) in each ink cartridge IC, and a light-receiving portion 94(light-receiving device) that receives reflected light from the prism170 and converts it into an electric signal.

FIG. 6 is an illustrative diagram showing an electric configuration ofthe detection portion. For example, the detection portion 90 includes anLED (Light Emitting Diode) as the light-emitting portion 92(light-emitting device), and includes a phototransistor as thelight-receiving portion 94 (light-receiving device). An emitter terminalof the light-receiving portion 94 is grounded, and a collector terminalthereof is connected to power supply potential Vcc via a resistor R1.Electric potential between the resistor R1 and the collector terminal isinput, as output voltage Vc (detection voltage) of the detection portion90, to a remaining amount determination portion 42, details of whichwill be described later.

The amount of the light radiated by the light-emitting portion 92 is setby a duty ratio (ratio between on-time and off-time) of a PWM (PulseWidth Modulation) signal applied to the light-emitting portion 92 beingadjusted by the control unit 40. When the radiated light that isradiated from the light-emitting portion 92 is reflected at the prism170 in each ink cartridge IC and the reflected light is received by thelight-receiving portion 94, the output voltage Vc corresponding to theamount of the received light is input as an output signal to theremaining amount determination portion 42. In the present embodiment, asthe amount of the light to be received by the light-receiving portion 94is larger, the output voltage Vc to be output from the detection portion90 is smaller.

However, the configuration of the light-receiving portion 94 is notlimited to that in FIG. 6, and a relationship between the amount oflight received by the light-receiving portion 94 and a detection signalof the detection portion 90 (the light-receiving portion 94) is notlimited to the above-described relationship either. For example, withthe configuration of the light-receiving portion 94 shown in FIG. 7, thelarger the amount of light received by the light-receiving portion 94 isand the larger the amount of generated current is, the larger thedifference between the output voltage Vc and a ground potential VSS is.That is to say, the larger the amount of light received by thelight-receiving portion 94 is, the higher the output voltage Vc outputfrom the detection portion 90 is.

Considering that the detection portion 90 is originally for detectingthe amount of incident light and the light-receiving portion 94 is adevice that converts light into current, the output of the detectionportion 90 may be essentially considered to be the amount of currentgenerated at the light-receiving portion 94. Considering it to be theamount of current, a relationship is established in which the strongerthe incident light is, the larger the output current is. Accordingly,the amount of incident light can be determined regardless of theconfiguration. The following is a description of an example in which theconfiguration of the light-receiving portion 94 shown in FIG. 6 isemployed, and it is accordingly assumed that the larger the amount ofincident light is, the larger the amount of generated current is and thelower the output voltage Vc is. However, “the output voltage being low(high)” in the following description can be essentially considered to be“the amount of generated current being large (small)”, and the form ofthe output signal that the amount of current is detected in can bemodified in various manners.

As shown in FIGS. 4 and 5, the light-emitting portion 92 and thelight-receiving portion 94 provided in the detection portion 90 arearranged so as to be aligned with the main scanning direction HD (Y-axisdirection) in which the holder 20 moves. The holder 20 is relativelymoved with respect to the detection portion 90 in the main scanningdirection HD by the carriage motor 33. The light-emitting portion 92 andthe light-receiving portion 94 are arranged so as to face the prism 170in each ink cartridge IC via a corresponding opening portion 22 (seeFIG. 9B) of the holder 20 when the holder 20 is moved by the carriagemotor 33 and is located above the detection portion 90. A face of thedetection portion 90 in which the light-emitting portion 92 and thelight-receiving portion 94 are arranged is arranged substantiallyparallel with the prism bottom face.

The control unit 40 has the remaining amount determination portion 42and a position correction portion 44. A display unit 46 on which anoperation state or the like of the printer 10 is displayed is connectedto the control unit 40. A computer 48 is connected to the control unit40 via an interface (I/F) 47. Furthermore, the carriage CR is connectedto the control unit 40 via the cable FFC1, and the detection portion 90is connected to the control unit 40 via a cable FFC2.

The control unit 40 includes a CPU, a ROM, a RAM, and the like (notshown). The CPU functions as the remaining amount determination portion42 and the position correction portion 44 by deploying control programsstored in advance in the ROM onto the RAM and executing it. The controlunit 40 also controls printing on the print medium PA by controlling thepaper feed motor 30, the carriage motor 33, and the print head 35.

The remaining amount determination portion 42 determines, using thedetection portion 90 and the prism 170, the amount of remaining ink ineach ink cartridge IC. The remaining amount determination portion 42acquires the output voltage Vc (detection voltage) at the time when theprism 170 is located at a predetermined position (detection position)with respect to the detection portion 90, from the detection portion 90via the cable FFC2. The remaining amount determination portion 42 thendetermines whether or not the amount of the ink in each ink cartridge IChas become smaller than or equal to a predetermined amount, based on theacquired output voltage Vc and a predetermined threshold value. Thestate where the amount of remaining ink has become smaller than or equalto the predetermined amount will be hereinafter referred to also as an“ink near-end” state.

Regarding the ink cartridge IC that is in the ink near-end stateaccording to the determination, the control unit 40 outputs aninstruction to display an alarm for indicating ink replacement to thedisplay unit 46 of the printer 10 and a display unit of the computer 48,and thus prompts a user to replace the ink cartridge IC. The controlunit 40 determines that the ink cartridge IC is empty when apredetermined amount of the ink is consumed after it is determined thatthe ink cartridge IC is in the ink near-end state. The control unit 40may determine that the ink cartridge IC is empty when determining thatthe ink cartridge IC is in the ink near-end state. If the control unit40 determines that the ink cartridge IC is empty, the control unit 40does not execute printing until the ink cartridge IC is replaced.

The position correction portion 44 corrects information of the positionof each prism 170 with respect to the detection portion 90 in the mainscanning direction HD, based on the detection voltage (output voltageVc) from the detection portion 90. If the actual relative position ofthe prism 170 with respect to the detection portion 90 is shifted fromthe designed relative position thereof, the accuracy of the ink near-enddetermination for the ink cartridges IC decreases. For this reason, therelative position of the holder 20 (prism 170) with respect to thedetection portion 90 at the time when the ink near-end determination isperformed is corrected based on the reflected light from the reflectionportion 24. The details will be described later. Also, peak detectionmay be performed on the detection voltage from the detection portion 90for each ink cartridge IC, and the relative position may be correctedusing the detected peak position as well.

The position of the carriage CR (holder 20) is perceived based on theoutput of a rotary encoder carried in the carriage motor 33. That is tosay, the rotary encoder outputs a count value corresponding to theamount of movement from the home position of the carriage CR, which isregarded as a reference position, for example. A predetermined countvalue of the rotary encoder corresponds to the center position of theprism 170 in each ink cartridge IC. Prior to the position correction,the count value corresponding to each position is mechanically set basedon a design value, and is stored in an EEPROM (nonvolatile memory) inthe control unit 40, for example. The position correction portion 44corrects the count value corresponding to each position by performingposition correction processing and writes the corrected count value inthe RAM and the EEPROM in the control unit 40, and the remaining amountdetermination portion determines, based thereon, the amount of remainingink in the ink cartridges.

FIG. 8 is a perspective view of an ink cartridge. Each ink cartridge ICincludes a substantially rectangular-parallelepiped ink containingchamber 130 that contains ink, a circuit board 150, and a lever 120 forattaching and detaching the ink cartridge IC to/from the holder 20.

The prism 170, which has a rectangular equilateral triangle columnshape, is arranged in a bottom portion (a face in the −Z direction) ofthe ink containing chamber 130. A bottom face 170 c of the prism 170that is a face facing the detection portion 90 is an incident face thatthe radiated light from the light-emitting portion 92 (see FIG. 5)enters, and is exposed from a bottom face 101 of the ink cartridge ICthat is a face on the side in the −Z direction.

An ink supply port 110, into which an ink receiving needle (not shown)provided in the holder 20 is inserted when the ink cartridge IC isinstalled in the holder 20, is formed in the bottom face 101 of the inkcartridge IC. In a state where the ink cartridge IC is unused, the inksupply port 110 is sealed by a film. Upon the ink cartridge IC beinginstalled from above into the holder 20 (see FIG. 4), the film is tornby the ink receiving needle, and the ink is supplied from the inkcontaining chamber 130 to the print head 35 through the ink supply port110.

A storage device 151 for recording information related to the inkcartridge IC is attached to a back face of the circuit board 150. Aplurality of terminals 152 that are electrically connected to thestorage device 151 are arranged in a front face of the circuit board150. When the ink cartridge IC is installed in the holder 20, theterminals 152 come into electric contact with a plurality of bodyterminals (not shown) provided in the holder 20.

These body terminals are electrically connected to the control unit 40via the cable FFC1. Thus, when the ink cartridge IC is installed in theholder 20, the control unit 40 is electrically connected to the storagedevice 151, and can read and write data from/to the storage device 151.As the storage device 151, for example, a nonvolatile memory such as anEEPROM can be used.

3. CONFIGURATION OF HOLDER

FIGS. 9A and 9B are diagrams illustrating a configuration of the holderaccording to the present embodiment. FIG. 9A is a schematic view of abottom face (bottom portion) of the holder 20 as seen from the side ofthe detection portion 90. FIG. 9B is a schematic view of a YZcross-section of the holder 20 in which the ink cartridges IC areinstalled. FIG. 9B corresponds to a cross-sectional view taken alongline 9B-9B in FIG. 9A. As shown in FIGS. 9A and 9B, a portion of thebottom face 21 of the holder 20 that corresponds to the prism and facesthe detection portion 90 has an inclined face 21 d that inclines in themain scanning direction HD (Y-axis direction).

The bottom face 21 of the holder 20 also has, for example, four openingportions 22 that are provided so as to be aligned with the main scanningdirection HD. Each opening portion 22 is arranged so as to be sandwichedbetween portions of the inclined face 21 d in the main scanningdirection HD. In other words, the inclined face 21 d is arranged betweenthe opening portions 22 that are adjacent to each other in the mainscanning direction HD, and on both outer sides of the four openingportions 22 in the main scanning direction HD. Four ink cartridges IC1to IC4 are installed in the holder 20 at positions corresponding to therespective opening portions 22.

A light-blocking portion 23 that blocks the radiated light from thelight-emitting portion 92 is provided at the center of each openingportion 22 so as to cover a part of the opening portion 22. The centerof each opening portion 22 is a position corresponding to the edge line(center) of the prism 170 when the corresponding ink cartridge IC isinstalled in the holder 20, at the time of designing the printer and theink cartridge. The center positions of two adjacent opening portions 22are separate from each other by the distance b1. Accordingly, the centerpositions of adjacent light-blocking portions 23 are separate from eachother by the distance b1. This distance b1 is mechanically set based ona design value.

The light-blocking portions 23 are provided in the sub-scanningdirection VD (X-axis direction) intersecting the main scanning directionHD (Y-axis direction), and each divide the corresponding opening portion22 of the holder 20 into two parts, namely an opening portion 22 a andan opening portion 22 b (see later-described FIGS. 13A and 13B). Eachlight-blocking portion 23 is arranged at a position facing the edge lineof the corresponding prism 170. At the detection position whenperforming the ink near-end determination, the opening portion 22 a,which is a part of each opening portion 22 divided into two parts by thecorresponding light-blocking portion 23, is located at a position atwhich the light-emitting portion 92 and the inclined face 170R face eachother, and the opening portion 22 b, which is the other part of eachopening portion 22, is located at a position at which thelight-receiving portion 94 and the inclined face 170L face each other.

An inclined face that inclines in the main scanning direction HD (Y-axisdirection) is provided in each light-blocking portion 23 on the side ofthe detection portion 90. The light-blocking portions 23 are made of alight-absorbing material, such as black-colored polystyrene, forexample. In the present embodiment, the light-blocking portions 23 aremade of the same material as that of the holder 20, and are formedintegrally therewith. In this case, a face of the light-blocking portion23 that faces the detection portion 90 is included in the bottom face 21of the holder 20. However, the material of the light-blocking portions23 is not limited to the aforementioned material, and any material maybe applied that can suppress the reflected light entering thelight-receiving portion 94. A configuration may be employed in which thelight-blocking portion 23 is formed as a body separate from the holder20 and is attached to the holder 20, and in this case, the face of thelight-blocking portion 23 does not constitute the bottom face 21 of theholder 20.

A recess portion 26 is formed near an end portion of the bottom face ofthe holder 20 on the side in the +Y direction, and a reflection portion24 (reflecting plate, position correction plate, failure detectionplate) serving as a reflective area is provided in the bottom face ofthe recess portion 26. The reflection portion 24 is provided at a placefacing the light-emitting portion 92 and the light-receiving portion 94when the reflection portion 24 is located immediately above thedetection portion 90 as a result of the holder 20 moving back and forth.The reflection portion 24 is formed by a mirror capable of totallyreflecting incident light. When the reflection portion 24 is locatedimmediately above the detection portion 90, upon the light radiated fromthe light-emitting portion 92 entering the reflection portion 24, thereflected light that is totally reflected at the reflection portion 24enters the light-receiving portion 94. Note that the reflection portion24 may be formed by coating the bottom face of the recess portion 26 ofthe holder 20 with a reflector, rather than providing the reflectionportion 24 as a separate body that can be separated from the holder 20.

Non-reflective members serving as non-reflective areas having a lowerreflectance than that of the reflection portion are provided at bothends of the recess portion 26 in the main scanning direction HD (Y-axisdirection), i.e., both ends of the reflection portion 24 in the mainscanning direction HD when the reflection portion 24 is seen from theside of the detection portion 90. The non-reflective members are made ofa light-absorbing material, and the bottom faces of the non-reflectivemembers (the bottom face of the holder) when seen from the side of thedetection portion 90 inclines with respect to the sub-scanning directionVD (X-axis direction). In the present embodiment, the non-reflectivemembers are made of black-colored polystyrene, for example, and thebottom faces thereof incline at a predetermined angle θ relative to thesub-scanning direction VD. The non-reflective member is made of the samematerial as the holder and is integrally formed therewith. Note that, asmentioned above, the non-reflective members include the first portion,which is a portion peripheral to the reflection portion 24 and havinginclined faces inclining in the sub-scanning direction in the presentembodiment. Here, since the non-reflective members are provided in theareas corresponding to these inclined faces, the portions where thenon-reflective members are provided coincide with the first portion.However, a modified mode is possible in which the non-reflective membersare provided in portions other than the first portion, for example.

As shown in FIGS. 9A and 9B, the center position of the reflectionportion 24 is separate in the main scanning direction HD from the centerposition of the adjacent opening portion 22 by the distance b0. Thecenter position of this opening portion 22 is separate from the centerposition of the opening portion 22 adjacent thereto on the side oppositeto the reflection portion 24 by the distance b1. The center positions ofother two adjacent opening portions 22 are also separate from each otherby the distance b1.

The prisms 170 provided in the ink containing chambers 130 of the inkcartridges IC1 to IC4 each have an inclined face 170R and an inclinedface 170L. The inclined face 170R and the inclined face 170L constitutean edge line of the prism 170 that is aligned with the sub-scanningdirection VD (X-axis direction) intersecting the main scanning directionHD (Y-axis direction). The prism 170 has a rectangular equilateraltriangle shape with a vertex angle formed by the inclined face 170R andthe inclined face 170L, as seen from the X-axis direction.

The prism 170 is made of a member, such as polypropylene, that transmitsthe radiated light from the light-emitting portion 92. The state ofreflection of the radiated light entering each prism 170 from thelight-emitting portion 92 differs depending on the refractive index of afluid (ink or air) that is in contact with the inclined faces 170R and170L. The opening portions 22 are arranged at positions facing thelight-emitting portion 92 and the light-receiving portion 94 provided inthe detection portion 90 when the respective prisms 170 in the inkcartridges IC1 to IC4 are located immediately above the detectionportion 90 as a result of the holder 20 moving back and forth.

Upon the carriage CR including the holder 20 moving in the main scanningdirection HD (Y-axis direction), the ink cartridges IC1 to IC4sequentially pass above the detection portion 90 (+Z direction). Then,the radiated light from the light-emitting portion 92 is reflected atthe prism 170 in each ink cartridge IC through the corresponding openingportion 22, and the reflected light is received by the light-receivingportion 94. The detection portion 90 outputs a result of light receptionby the light-receiving portion 94 as an output signal corresponding tothe position of the carriage CR (prism 170). In the present embodiment,the ink near-end determination for each ink cartridge IC and correctionof the detection position for performing the ink near-end determinationare performed, based on this output signal of the detection portion 90that corresponds to the position of the carriage CR.

FIG. 10 is a diagram for illustrating a state of reflected light at thetime when light is radiated from the light-emitting portion 92. Theholder 20 shown in FIG. 10 is driven by the aforementioned carriagemotor 33, and thereby moves back and forth in the main scanningdirection HD above the detection portion 90 fixed to the printer 10.When the holder 20 moves above the detection portion 90, the positionalrelationship between the holder 20 and the detection portion 90relatively changes, as indicated by exemplary positions Pr, P1, and P2shown in FIG. 10.

At the position Pr, the detection portion 90 faces the reflectionportion 24 provided in the bottom face of the recess portion 26. At thisposition, the reflection portion 24 is located immediately above thedetection portion 90, and the center position between the light-emittingportion 92 and the light-receiving portion 94 substantially coincideswith the center position of the reflection portion 24 in the mainscanning direction HD. When the reflection portion 24 is locatedimmediately above the detection portion 90, since the reflection portion24 is made of a mirror, light R25 radiated from the light-emittingportion 92 toward the reflection portion 24 is totally reflected at thereflection portion 24, and this reflected light is received by thelight-receiving portion 94.

Note that the configuration of the holder 20 according to the presentembodiment is not limited to the above-described configuration. Forexample, the first portion (the holder bottom face 21 peripheral to thereflection portion 24) of the holder 20 may have a plurality of steps ofinclined faces that incline in the second direction. FIG. 11 is adiagram illustrating the holder 20 having the plurality of steps ofinclined faces. FIG. 11 is a schematic diagram of an XZ cross-sectionenlarging one side of the bottom face (the first portion) of the holder20 indicated by oblique lines in FIG. 9A.

As shown in FIG. 11, for example, three inclined faces 27 a to 27 c areprovided in a saw blade-like shape in the X-axis direction in the firstportion of the holder 20. The length and the inclination angle of theinclined faces 27 a to 27 c in the X-axis direction are substantiallythe same.

As described above using FIG. 1B, the longer the distance from thedetection portion 90 to the bottom face of the holder 20 is (i.e., ifdescribed based on the height relative to the aforementioned reflectionportion 24, the lower the height of the holder 20 is), the more likelythe position correction processing is to be affected by ambient lightdue to it. For this reason, the distance from the detection portion 90to the holder 20 is to be as small as possible, while taking therelationship with other elements into consideration as well.

A comparison between the case where one inclined face is provided in theholder 20 and the case where a plurality of steps of inclined faces areprovided therein is shown in FIGS. 12A and 12B. If the holder 20 has theplurality of steps of inclined faces that are arranged in a sawblade-like shape as in FIG. 11, the position of the holder bottom faceon the Z-axis is within a range Rz1, as shown in FIG. 12A. Although thedistance between the detection portion 90 and the holder 20 varies if ashift occurs in the relative positions thereof in the sub-scanningdirection, the distance to a point E1 or E3 need only be considered tobe the maximum distance in the case of FIG. 12A.

In contrast, in the case of one inclined face, the shape of the holderbottom face 21 is as shown in FIG. 12B. If the position shift of thedetection portion 90 relative to the holder 20 in the sub-scanningdirection is within the range from +1 to −1, the position of the holderbottom face on the Z-axis varies in a range Rz2, as shown in FIG. 12B.For this reason, in the case of FIG. 12B, the distance to E5 needs to beconsidered to be the maximum distance between the detection portion 90and the holder 20.

As is also clear from FIGS. 12A and 12B, as a result of providing aplurality of steps of inclined faces, the distance between the detectionportion 90 and the holder 20 can be expected to be shortened. As aresult, it is possible to suppress the influence of ambient light andperform accurate position correction processing.

Note that, in the case of providing a plurality of inclined faces (here,first to Nth inclined faces) and shortening the distance between thedetection portion 90 and the holder 20, a configuration of may beemployed in which the first portion of the holder 20 has the first toNth (N is an integer larger than or equal to 2) inclined faces arrangedin the second direction, and the distance between the detection portion90 and the holder 20 at an end point of an ith (i is an integer thatsatisfies 1≦i<N) inclined face on the side of an i+1th inclined face islarger than the distance between the detection portion 90 and the holder20 at an end point of the i+1th inclined face on the side of the ithinclined face.

Here, in the example in FIG. 12A, N=3, and a first inclined face, asecond inclined face, and a third inclined face correspond to 27 a, 27b, and 27 c, respectively. If i=1, the end point of the ith inclinedface on the side of the i+1th inclined face corresponds to the end pointE1 of the inclined face 27 a in the −X direction, and if i=2, itcorresponds to the end point E3 of the inclined face 27 b in the −Xdirection. Similarly, if i=1, the end point of the i+1th inclined faceon the side of the ith inclined face corresponds to the end point E2 ofthe inclined face 27 b in the +X direction, and if i=2, it correspondsto the end point E4 of the inclined face 27 c in the +X direction. Notethat each inclined face here is a face whose direction in the Z-axisdirection from the plane in which the detection portion 90 is arrangedmonotonously increases (i.e., whose Z-axis coordinate value monotonouslyincreases) in the direction (the −X direction) from the ith inclinedface toward the i+1th inclined face.

Considering the direction from the ith inclined face toward the i+1thinclined face, within the ith inclined face, the distance from thedetection portion 90 is largest at the position at which this inclinedface ends, i.e., at the end point (E1) on the side of the i+1th inclinedface. At the position (E2) where the ith inclined face ends and thei+1th inclined face starts, the distance to the detection portion 90shortens once (the distance between the detection portion 90 to E2<thedistance between the detection portion 90 to E1) due to theaforementioned condition. As an example, as shown in FIG. 12A, thedistance at the start point of the i+1th inclined face need only be madeequal to the distance at the start point of the ith inclined face.

With this configuration, the distance to the detection portion 90necessarily decreases once at the joint between two inclined faces amongthe plurality of inclined faces, and it is accordingly possible toreduce the expected value of the distance in the Z-axis direction to theplane in which the detection portion 90 is arranged, as compared withthe holder having one inclined face without a point at which thedistance decreases as in FIG. 12B. For example, when the distance in theZ-axis direction between the point at which an inclined face starts andthe plane in which the detection portion 90 is arranged is the same, thedistance in the Z-axis direction between the end point and the plane inwhich the detection portion 90 is arranged can be reduced.

As described above, a plurality of liquid containers can be attached toand detached from the holder 20 according to the present embodiment, andthe holder 20 can hold the liquid containers. The holder 20 has theplurality of opening portions 22 each provided at a position facing thecorresponding prism among the plurality of prisms 170 when the pluralityof liquid containers are installed. Although the inclined facesinclining in the sub-scanning direction are provided in the firstportion of the holder 20 peripheral to the reflection portion 24 in thepresent embodiment, this first portion may be a portion defined based onthe positions of the reflection portion 24 and the plurality of openingportions 22. For example, the first portion may be a portion between thereflection portion 24 and a first opening portion among the plurality ofopening portions 22.

In the case of FIG. 9A, a first area in which the inclined facesinclining in the sub-scanning direction according to the presentembodiment is constituted by two portions indicated by oblique lines.The first area includes an area between the reflection portion 24 andthe opening portion 22, i.e., an area on the side in the −Y direction ofthe two oblique-line areas in FIG. 9A. Note that the first openingportion here need only be the opening portion provided at a positionclosest to the reflection portion 24 among the plurality of openingportions 22, for example. In the example in FIG. 9A, the first openingportion is the opening portion 22 corresponding to the ink cartridgeIC1.

However, the first portion that is peripheral to the reflection portion24 and has the inclined faces inclining in the sub-scanning direction isnot limited to the portion between the reflection portion 24 and thefirst opening portion. For example, the first portion may be a portionon the side opposite to the first opening portion among the plurality ofthe opening portion 22 with respect to the reflection portion 24.

That is to say, the first area includes an area opposite to the openingportions 22 with respect to the reflection portion 24, i.e., the area onthe side in the +Y direction of the two oblique-line areas in FIG. 9A.Note that the “opposite side” here need only be considered based on themain scanning direction HD. For example, the space on the side thatincludes the first opening portion and the space on the side that doesnot include the first opening portion can be conceived by dividing thespace into two by a plane (an XZ plane) that is centered about thereflection portion 24 and is orthogonal to the main scanning directionHD. In this case, the portion on the side opposite to the first openingportion is a portion located in the space that does not include thefirst opening portion of the aforementioned two spaces.

In the present embodiment, the inclined faces inclining in thesub-scanning direction are provided at two portions indicated by obliquelines in FIG. 9A. That is to say, the aforementioned first portionrefers to, in the narrow sense, both a portion between the reflectionportion and the first opening portion among the plurality of openingportions 22 and a portion on the side opposite to the first openingportion among the plurality of opening portions 22 with respect to thereflection portion 24.

Each of the portions between the plurality of opening portions hasinclined faces inclining in the first direction, as shown in FIG. 9B.

As described later, in the ink near-end determination as well,reflection at the bottom face of the holder 20 is a noise factor thatdecreases the determination accuracy. For this reason, inclined facesmay also be provided in portions peripheral to the prisms 170. In theink near-end determination, the light that is originally to be detectedis reflected light from the prisms 170, and is accordingly weaker lightthan the reflected light at the reflection portion 24. For this reason,noise needs to be more sufficiently reduced than in the positioncorrection processing, and it is also important to suppress reflectionat the bottom face of the holder 20.

However, in the ink near-end determination, a predetermined thresholdvalue is compared with a signal level, as described later using FIG.14B. At this time, the distance between the detection portion 90 and theholder 20 directly affects the signal level, and variation of thisdistance is not favorable. Variation here refers to variation due to ashift of the relative positions of the holder 20 and the detectionportion 90 in the sub-scanning direction, as shown in FIG. 12B.

While there is a difference in the variation range between the case of aplurality of steps and the case of one inclined face as shown in FIGS.12A and 12B, when the inclined faces incline in the sub-scanningdirection, the distance between the holder 20 and the detection portion90 varies due to a relative position shift between the holder 20 and thedetection portion 90 in the sub-scanning direction. For this reason, thesignal level changes in accordance with the position shift, and there isa possibility that appropriate ink near-end determination cannot beperformed with a preset threshold value.

Accordingly, in the holder 20 in the present embodiment, the incliningdirection of the inclined faces is a direction parallel with the mainscanning direction HD in the portions peripheral to the prisms 170.However, if a configuration is possible in which a relative positionshift between the holder 20 and the detection portion 90 in thesub-scanning direction can be sufficiently suppressed, or in which, evenif a position shift occurs, this shift does not cause variation of thesignal level which affects the ink near-end determination, the inclinedfaces may be configured to incline in the sub-scanning direction VD alsoin the portions peripheral to the prisms 170.

4. INK NEAR-END DETERMINATION TECHNIQUE

Next, the ink near-end determination method according to the presentembodiment will be described. FIGS. 13A and 13B and FIGS. 14A and 14Bare diagrams illustrating the ink near-end determination method. FIGS.13A and 13B show a cross-section in a YZ plane that passes through theprism 170 in each ink cartridge IC. FIGS. 13A and 13B each show a statewhere the positional relationship between the prism 170 and thedetection portion 90 is a positional relationship (detection position)in which the amount of remaining ink can be detected for the inknear-end determination.

FIG. 14A shows a cross-section in a YZ plane that passes through theprism 170 in each ink cartridge IC. FIG. 14A shows a state where thepositional relationship between the prism 170 and the detection portion90 is not a positional relationship in which the amount of remaining inkcan be detected for the ink near-end determination. FIG. 14B shows anexemplary characteristic of detection voltage when one of the inkcartridges IC passes above the detection portion 90.

As shown in FIG. 13A, the inclined faces 170R and 170L of the prism 170face inward of the ink containing chamber 130. The inclined face 170R isa face perpendicular to the inclined face 170L, for example, and theinclined face 170R and the inclined face 170L are arranged symmetricallywith respect to a plane parallel with an XZ plane. When the inkcontaining chamber 130 is filled with the ink IK, the inclined faces170R and 170L are in contact with the ink IK.

When the ink cartridge IC is filled with the ink IK, radiated light Leentering the prism 170 from the light-emitting portion 92 enters the inkIK from the inclined face 170R. In this case, the amount of reflectedlight Lr reflected at the inclined faces 170R and 170L is very small,and accordingly the light-receiving portion 94 hardly receives thelight. For example, assuming that the refractive index of the ink is1.5, which is almost similar to the refractive index of water, if theprism 170 is made of polypropylene, the critical angle of totalreflection at the inclined faces 170R and 170L is approximately 64degrees. Since the incident angle is 45 degrees, the radiated light Leis not totally reflected at the inclined faces 170R and 170L, and entersthe ink IK.

Suppose that, as shown in FIG. 13B, the ink IK in the ink cartridge ICis consumed for printing, and the ink cartridge IC is not filled withthe ink IK. It is assumed that, of the inclined faces 170R and 170L ofthe prism 170, at least a part that the radiated light Le from thelight-emitting portion 92 enters is in contact with the air. In thiscase, the radiated light Le entering the prism 170 from thelight-emitting portion 92 is totally reflected at the inclined faces170R and 170L, and exits as the reflected light Lr to the outside of theprism 170.

Accordingly, when the ink cartridge IC is not filled with the ink IK,the light-receiving portion 94 receives the totally reflected light Lr,and accordingly, strong detection voltage is obtained. For example, in acase where the refractive index of the air is 1 and the prism 170 ismade of polypropylene, the critical angle of total reflection at theinclined faces 170R and 170L is approximately 43 degrees. Since theincident angle is 45 degrees, the radiated light Le entering the prism170 is totally reflected at the inclined faces 170R and 170L.

In FIG. 14B, the horizontal axis indicates relative positions of theprism 170 and the detection portion 90, and the vertical axis indicatesdetection voltage that is output from the detection portion 90 at eachposition on the horizontal axis. The position at the time when thecenter of the prism 170 coincides with the center of the detectionportion 90 (e.g., the positional relationship between the ink cartridgeIC and the detection portion 90 shown in FIG. 13A) is “0” on thehorizontal axis. The center of the detection portion 90 is the centerbetween the light-emitting portion 92 and the light-receiving portion 94in the main scanning direction HD.

A position PK1 is a position at which the relative positions of thecenter of the prism 170 and the center of the detection portion 90 areshifted from the position “0” in the main scanning direction HD, andthat corresponds to the opening portion 22 b of the holder 20, as in thepositional relationship between the ink cartridge IC and the detectionportion 90 shown in FIG. 14A. Similarly, a position PK2 is a position atwhich the relative positions of the center of the prism 170 and thecenter of the detection portion 90 are shifted from the position “0” inthe main scanning direction HD, and that corresponds to the openingportion 22 a of the holder 20.

As shown in FIG. 14B, the detection voltage approaches upper limitvoltage Vmax as the amount of light received by the light-receivingportion 94 is closer to zero, and the detection voltage approaches lowerlimit voltage Vmin as the amount of light received by thelight-receiving portion 94 is larger. When the amount of received lightexceeds a predetermined value, the detection voltage is saturated andreaches the lower limit voltage Vmin. The upper limit voltage Vmax andthe lower limit voltage Vmin correspond respectively to upper limitvoltage and lower limit voltage in the range of voltage that thelight-receiving portion 94 outputs to the collector terminal in FIG. 3,for example.

The detection voltage that is output from the detection portion 90varies in accordance with the relative positions of the detectionportion 90 and the prism 170. SIK indicates a detection voltagecharacteristic in the case where the ink cartridge IC is filled with theink IK, as described in FIG. 13A. In this case, since the amount oflight received by the light-receiving portion 94 is small, the detectionvoltage is close to Vmax at the position “0”. At the positions PK1 andPK2 at which the relative positions of the center of the prism 170 andthe center of the detection portion 90 are shifted from the position “0”in the main scanning direction HD, peaks Spk1 and Spk2 are respectivelygenerated due to the reflected light Lr from the bottom face 170 c ofthe prism 170. These peaks Spk1 and Spk2 will be described later.

SEP indicates a detection voltage characteristic in the case where theink cartridge IC is not filled with the ink IK, as described in FIG.13B. In this case, since the amount of light received by thelight-receiving portion is large, the detection voltage reaches Vmin (orapproaches Vmin) at the position “0”. Thus, the characteristic of thedetection voltage significantly differs depending on whether or not theink cartridge IC is filled with the ink IK. In the present embodiment,the ink near-end determination for each ink cartridge IC is performed bydetecting this difference in the detection voltage characteristic.

Specifically, a threshold value Vth is set between a peak value Vpk1 andthe lower limit voltage Vmin, based on the peak value Vpk1 of thedetection voltage characteristic SIK. In a detection range DPR in whichthe ink cartridge IC passes above the detection portion 90, if thedetection voltage of the detection portion 90 is smaller than thethreshold value Vth, it is determined that the ink cartridge IC is inthe ink near-end state. If the detection voltage is larger than or equalto the threshold value Vth, it is determined that the ink is remaining.

As shown in FIG. 14A, the light-blocking portion 23 that blocks thelight from the light-emitting portion 92 is provided at the center ofeach opening portion 22 of the holder 20. A part of the radiated lightLe entering the bottom face 170 c of the prism 170 from thelight-emitting portion 92 is reflected at the bottom face 170 c, and isreceived as the reflected light Lr by the light-receiving portion 94.The reflection angle of this reflected light Lr at the bottom face 170 cis equal to the incident angle of the radiated light Le at the bottomface 170 c. As indicated by the detection voltage characteristic SIK inFIG. 14B, the reflected light Lr from the bottom face 170 c is notdetected at the position since the light-blocking portion 23 is present,and the peaks Spk1 and Spk2 are detected respectively at the positionsPK1 and PK2 since the light-blocking portion 23 is not present.

Here, the position PK1 is the position at which the center of theopening portion 22 b and the center of the detection portion 90 in themain scanning direction HD coincide with each other, and the positionPK2 is the position at which the center of the opening portion 22 a andthe center of the detection portion 90 in the main scanning direction HDcoincide with each other. Note that, although the reflected light Lrfrom the bottom face 170 c is also detected when totally reflected lightreturns from the prism 170, the peaks Spk1 and Spk2 are not generatedsince the detection voltage is buried in the signal of the totallyreflected light, as indicated by the detection voltage characteristicSEP.

FIG. 15 is a flowchart showing ink near-end determination processing.The ink near-end determination processing is executed at a timing suchas when starting the printer 10 or when replacing the ink cartridges IC,for example.

As shown in FIG. 15, in the ink near-end determination processing,initially, the control unit 40 (the position correction portion 44)performs the position correction processing in the main scanningdirection HD for the respective prisms 170 in the ink cartridges IC1 toIC4 (step S10). The details of the position correction processing willbe described later.

Next, in step S20, the control unit 40 moves the holder 20 in the mainscanning direction HD such that the prisms 170 in the ink cartridges IC1to IC4 pass above the detection portion 90. Here, the reflected lightradiated from the light-emitting portion 92 and reflected at the prisms170 in the ink cartridges IC1 to IC4 is received by the light-receivingportion 94 at the positions P1′ to P4′ after the correction processingin step S10.

Subsequently, the control unit 40 reads the detection voltage (theoutput voltage Vc) of the detection portion 90 (the light-receivingportion 94) corresponding to the amount of the reflected light from therespective prisms 170 in the ink cartridges IC1 to IC4 in the detectionrange including the positions P1′ to P4′ after the correction (stepS30).

Next, the control unit 40 (the remaining amount determination portion42) compares the detection voltage of the determination target inkcartridge IC with a detection voltage threshold value for the inknear-end determination, based on the result of measurement of thedetection voltage in step S30 (step S40).

If the detection voltage of the determination target ink cartridge IC issmaller than the threshold value (step S40: YES), the control unit 40determines that the determination target ink cartridge IC is in the “inknear-end” state (step S50). On the other hand, if the detection voltageof the determination target ink cartridge IC is not smaller than thethreshold value (step S40: NO), the control unit 40 determines that “inkis remaining” in the determination target ink cartridge IC (step S60).

Next, the control unit 40 determines whether or not the ink near-enddetermination has finished for all ink cartridges IC1 to IC4 (step S70).If the ink near-end determination has finished for all ink cartridges IC(step S70: YES), the control unit 40 displays the amount of remainingink in the respective ink cartridges IC1 to IC4 (whether or not the inkcartridges IC1 to IC4 are in the ink near-end state), on the displayunit 46 provided in the printer 10 and the computer 48 connected to theprinter 10 (step S80).

On the other hand, if any ink cartridge IC remains for which the inknear-end determination has not finished (step S70: NO), the processingreturns to step S40, and the ink near-end determination is performed forthe remaining ink cartridge IC. Thus, it is sequentially determinedwhether or not the respective ink cartridges IC1 to IC4 are in the inknear-end state.

5. POSITION CORRECTION TECHNIQUE

The positions of the ink cartridges IC are shifted due to varioustolerances. Assumed tolerances include, for example, an inclination ofthe carriage CR, a shift in attachment thereof, an error of the rotaryencoder, and variation of a response speed of an electronic circuit(e.g., detection portion 90), or for example, a mechanical positionshift such as driving of the carriage. The control unit 40 perceives thepositions of the ink cartridges, based on the count value of the rotaryencoder, and these positions perceived by the control unit 40 areshifted from the actual positions of the ink cartridges IC due to thetolerances in some cases.

In a case of not correcting this position shift, it is necessary toconsider a position shift range including all expected tolerances anddetermine a detection range DPR in FIG. 14B so as to be able tocorrectly perform the ink near-end detection within this position shiftrange. Then, the detection range DPR becomes wider than the intervalbetween the two peaks Spk1 and Spk2, and the threshold value Vth cannotbe set close to the peak voltage Vpk1 at the peaks Spk1 and Spk2.

Then, if the peak in the case indicated by SEP where the ink runs out isalmost as large (Vpk1) as the peaks Spk1 and Spk2 caused due to thereflected light from the incident plane of the prism, the ink near-endstate will not be able to be correctly detected using the thresholdvalue Vth. This situation may occur when, for example, the amount ofemitted light and the amount of received light decrease since an inkmist is attached to the detection portion 90, and the ratio (so-calledS/N ratio) between noise including the peaks Spk1 and Spk2 and thedetection voltage generated due to total reflection becomes small.

For this reason, in the present embodiment, the position of each inkcartridge IC perceived based on the count value of the rotary encoder iscorrected based on the reflected light from the reflection portion 24.Since the position shift caused due to the tolerances is corrected bythis correction, the position of each ink cartridge IC can be associatedwith a count value of the rotary encoder with high accuracy.

Next, a position correction processing method in the present embodimentwill be described in detail, using a flowchart in FIG. 16. Initially,the control unit 40 causes the light-emitting portion 92 to emit light,and thereafter moves the holder 20 in the main scanning direction HDsuch that the reflection portion 24 provided in the holder 20 passesabove the detection portion 90. The control unit 40 then obtains thecenter position of the reflection portion 24 in the main scanningdirection HD, based on the reflected light from the reflection portion24 at the time when the reflection portion 24 passes above the detectionportion 90 (step S110). In the case of the example in FIGS. 17 and 18,the control unit 40 obtains the center position of the reflectionportion 24, based on a change of output voltage from a “non-reflectingperiod 1” to a “reflecting period (a period during which reflection fromthe reflection portion is received)”, then to a “non-reflecting period2” shown in FIG. 18. Specifically, initially, the control unit 40 sets athreshold value of the output voltage for the reflection portion 24.During the “reflecting period (reflection portion)”, the intersectionpoint of this threshold value and the gradually decreasing outputvoltage is regarded as one optical end Pr′1 of the reflection portion24, and the intersection point of the threshold value and the graduallyincreasing output voltage is regarded as the other optical end Pr′2 ofthe reflection portion 24. The control unit 40 then determines that thecenter position between the optical ends Pr′1 and Pr′2 is the centerposition Pr′ of the reflection portion 24. That is to say, the opticalposition corresponding to the center position Pr of the reflectionportion 24 shown in FIG. 17 is obtained as the center position Pr′ ofthe reflection portion 24 in FIG. 18, based on the output voltage fromthe detection portion 90.

Next, the control unit 40 corrects the position of the prism 170 in theink cartridge IC1, which is adjacent to the reflection portion 24, inthe main scanning direction HD, based on the center position of thereflection portion 24 obtained in step S110 (step S120). In the case ofthe example in FIGS. 17 and 18, the control unit 40 obtains the centerposition P1′ of the prism 170 in the ink cartridge IC1, based on theobtained center position Pr′ of the reflection portion 24, and performscorrection if a position shift has occurred with respect to the centerposition P1 serving as a reference point when the detection portion 90performs measurement. Specifically, initially, the control unit 40obtains the center position P1′ of the prism 170 in the ink cartridgeIC1, based on the obtained center position Pr′ of the reflection portion24. In the present embodiment, the distance b0 from the center positionPr of the reflection portion 24 to the center position P1 of the prism170 in the ink cartridge IC1 shown in FIG. 17 is 5 mm. Accordingly, theposition P1′ that is separate from the center position Pr′ of thereflection portion 24 by 5 mm shown in FIG. 18 is obtained as the centerposition P1′ of the prism 170. If the obtained center position P1′ ofthe prism 170 is different from the center position P1 of the prism 170serving as the reference point shown in FIG. 17, the center position ofthe prism 170 to be used when the detection portion 90 performsmeasurement is corrected in conformity to the center position P1′.

Next, the control unit 40 corrects the positions of the prisms 170 inthe other ink cartridges IC2 to IC4 in the main scanning direction HD,similarly to the prism 170 in the ink cartridge IC1, based on theinterval between adjacent opening portions 22 being the distance b1 asshown in FIG. 9A (step S130).

However, the position correction technique is not limited to theabove-described technique, and a detection signal corresponding to thereflection portion 24 and a detection signal corresponding to each inkcartridge may be used in combination. Specifically, a modification ispossible in which primary correction processing is performed forcorrecting the center position of each prism 170 based on the centerposition of the reflection portion 24 serving as a reference point.Then, peak detection is further performed on the detection voltage ofeach ink cartridge IC at the position after being subjected to theprimary correction, and secondary correction processing is performed forcorrecting the center position of each prism 170, based on the detectedpeak positions, thereby further improving the accuracy of the positioncorrection processing. For example, the following processing may beperformed as the secondary processing. Regarding a cartridge in whichink remains, the distance between the center position between twodetected peaks and the center position of the reflection portion isobtained. A difference between this distance and the designed distanceis obtained. The average of the differences among the cartridges isobtained. The center position of each cartridge is corrected,considering the averaged difference in addition to the designeddifference.

6. MODIFICATIONS

As described above, the liquid consuming apparatus in the presentembodiment includes a control portion (the control unit 40) thatperforms processing for correcting the positional relationship betweenthe holder 20 and the detection portion 90 when determining the amountof remaining liquid, based on the detection signal from the detectionportion 90 that indicates a result of reception of reflected light atthe reflection portion 24. However, the processing performed by thecontrol unit 40 is not limited thereto, and the control unit 40 can alsoperform other kind of processing. For example, the control portion canadjust the amount of light emitted from the light-emitting portion 92 inthe position correction processing. Furthermore, a failure in thedetection portion 90 can be detected, such as by determining that thedetection portion 90 has failed if the reflected light from thereflection portion 24 is not detected.

Also, a first liquid container and a second liquid container whosecapacity is smaller than that of the first liquid container may be ableto be attached to and detached from the holder 20, and the holder 20 maybe able to hold the first and second liquid containers. The reflectionportion 24 of the holder 20 may be provided on the side of the secondliquid container in the holder 20.

For example, in some existing printer products, the capacity of a blackink cartridge is about twice the capacity of other ink cartridges suchas a cyan ink cartridge. A configuration of the holder 20 in this caseis shown in FIGS. 19A and 19B. With the configuration of the holder 20shown in FIGS. 19A and 19B, the distance from an opening portioncorresponding to the ink cartridge IC4 (e.g., black) to the end point ofthe holder 20 on the side of this opening portion can be elongated,without changing the position of the opening portion 22.

Although the influence of ambient light in the periphery of thereflection portion 24 has been described in FIG. 1B, the fact thatambient light can cause noise also applies to the ink near-enddetermination using the prisms 170. As can be understood from FIG. 19B,the structure of the reflection portion 24 and the periphery thereof canfunction as a blocking portion that suppresses incidence of ambientlight during the ink near-end determination using the opening portions22 (particularly, the opening portion 22 corresponding to IC1).Specifically, since the distance from the end point of the holder 20 inthe main scanning direction to the opening portion 22 can be elongated,the influence of ambient light can be suppressed.

In a large-capacity ink cartridge, it is possible to similarly elongatethe distance from the end point of the holder 20 in the main scanningdirection to the opening portion 22 and suppress the influence ofambient light by arranging the prism 170 while biasing it to one side.That is to say, when an ink cartridge whose capacity is larger than thatof other ink cartridges is included, this ink cartridge is provided atan end portion of the holder 20 and can thereby function as a blockingportion.

With the above-described configuration, if the periphery of thereflection portion 24 and the large-capacity ink cartridge each functionas a blocking portion, the influence of ambient light can be efficientlysuppressed by providing an opening portion between the reflectionportion 24 and the large-capacity ink cartridge.

Although the holder 20 according to the above embodiment has aconfiguration in which the opening portions 22 are provided in thebottom face 21, the invention is not limited to this mode. The openingportions 22 need only be provided at positions at which the respectiveprisms 170 and the detection portion 90 face each other. For example,the opening portions 22 may be provided is in a side portion of theholder 20.

The holder 20 according to the above embodiments and modifications havea configuration in which four ink cartridges IC are installed, and thenumber of opening portions 22 corresponds to the number of the prisms170 in the ink cartridges IC. However, the invention is not limitedthereto. The number of installed ink cartridges IC and the number ofcorresponding opening portions 22, 52, 62, and 72 may be other thanfour.

The above embodiments and modifications have a configuration in whichthe light-emitting portion 92 and the light-receiving portion 94provided in the detection portion 90 are arranged so as to be alignedwith the main scanning direction HD (Y-axis direction) in which thecarriage CR moves. However, the invention is not limited to this mode.For example, a configuration may be employed in which the light-emittingportion 92 and the light-receiving portion 94 are arranged so as to bealigned with the direction (X-axis direction) perpendicular to the mainscanning direction HD.

The above embodiments and modifications have been described, taking, asan example, a case where the carriage CR moves in which the holders 20,20A, 50, 60, and 70 are carried, the ink cartridges IC1 to IC4 beingable to be attached to and detached from these holders, and thedetection portion 90 is fixed to the printer body. However, theinvention is not limited to this mode. For example, the carriage CR inwhich the detection portion 90 is carried may move, and the holders 20,20A, 50, 60, and 70, to and from which the ink cartridges IC1 to IC4 canbe attached and detached, may be fixed to the printer body. Anyconfiguration may be employed in which the ink cartridges IC1 to IC4 andthe detection portion 90 relatively move with respect to each other.Furthermore, a configuration may also be employed in which the holders20, 20A, 50, 60, and 70 are fixed, and the detection portion 90 isarranged in the carriage CR including the print head 35.

The above embodiments and modifications have been described, using anexample in which the invention is applied to a printer and inkcartridges. However, the invention is not limited to this mode. Forexample, the invention may also be used in a liquid consuming apparatusthat ejects and discharges liquid other than ink, and can also beapplied to a liquid vessel that contains such liquid. The liquid vesselof the invention can be used in various kinds of liquid consumingapparatus including a liquid ejection head that ejects minisculedroplets, and the like. “Droplets” refers to the state of the liquiddischarged from the liquid consuming apparatus, and includes dropletshaving a granular shape, a tear-drop shape, and a shape having athread-like trailing end. Furthermore, “liquid” mentioned here may beany kind of material that can be ejected by the liquid consumingapparatus. For example, the liquid need only be a material whosesubstance is in the liquid phase, and encompasses high or low viscosityliquid materials, as well as liquid materials such as sols, gel water,other inorganic solvents, organic solvents, solutions, liquid resins,and liquid metals (metal melts). Furthermore, the liquid is not limitedto being a one-state substance, and also encompasses a substance inwhich functional material particles made of a solid substance such aspigment or metal particles are dissolved, dispersed, or mixed in asolvent. Representative examples of the liquid include ink such as thatdescribed in the above embodiment, and liquid crystal. Here, “ink”encompasses general water-based ink and oil-based ink, as well asvarious types of liquid compositions such as gel ink and hot melt-ink.Specific examples of the liquid consuming apparatus may include, forexample, a liquid consuming apparatus that ejects liquid containing, inthe form of dispersion or dissolution, a material such as an electrodematerial or a color material to be used in manufacturing or the like ofa liquid crystal display, an EL (electro-luminescence) display, asurface-emitting display, or a color filter, a liquid consumingapparatus that ejects biological organic matter to be used inmanufacturing of a biochip, and a liquid consuming apparatus that isused as a precision pipette and ejects liquid serving as a sample.Furthermore, it is also possible to employ a liquid consuming apparatusthat ejects lubricating oil in a pinpoint manner to a precision machinesuch as a watch or a camera, a liquid consuming apparatus that ejectstransparent resin liquid such as ultraviolet-cured resin onto asubstrate, in order to form a micro-hemispherical lens (optical lens) orthe like to be used in an optical communication device or the like, or aliquid consuming apparatus that ejects an etchant that is acid,alkaline, or the like, for etching a substrate or the like.

The entire disclosure of Japanese Patent Application No. 2014-042990,filed on Mar. 5, 2014 is expressly incorporated herein by reference.

What is claimed is:
 1. A liquid consuming apparatus comprising: adetection portion having a light-emitting portion and a light-receivingportion; a holder configured to hold a plurality of liquid containers,each provided with a prism, each of the plurality of liquid containersbeing attachable to and detachable from the holder, the holder having aplurality of opening portions provided at positions facing the prismsrespectively when the liquid containers are installed, and a reflectionportion; and a moving portion that relatively moves the holder in afirst direction with respect to the detection portion, wherein thelight-emitting portion and the light-receiving portion are substantiallyaligned with the first direction, the plurality of opening portions andthe reflection portion are substantially aligned with the firstdirection, the reflection portion is positioned near an end portion ofthe holder on the side in the first direction, a first portion of theholder that is peripheral to the reflection portion in a plan view ofthe holder as seen from the side of the detection portion has aninclined face that inclines in a second direction intersecting the firstdirection, and a part between two adjacent opening portions has a faceinclined in the first direction.
 2. The liquid consuming apparatusaccording to claim 1, wherein the first portion has a plurality of stepsof inclined faces that incline in the second direction.
 3. The liquidconsuming apparatus according to claim 2, wherein the first portion hasa first to Nth (N is an integer larger than or equal to 2) inclinedfaces arranged in the second direction, and the distance between thedetection portion and the holder at an end point of an ith (i is aninteger that satisfies 1≦i<N) inclined face on the side of an i+1thinclined face is larger than the distance between the detection portionand the holder at an end point of the i+1th inclined face on the side ofthe ith inclined face.
 4. The liquid consuming apparatus according toclaim 1, further comprising a control portion that performs processingfor correcting a positional relationship between the holder and thedetection portion when determining the amount of remaining liquid, basedon a detection signal from the detection portion indicating a lightreception result of reflected light at the reflection portion.
 5. Theliquid consuming apparatus according to claim 1, wherein the firstportion is between the reflection portion and a first opening portionamong the opening portions.
 6. The liquid consuming apparatus accordingto claim 1, wherein the first portion is on the side opposite to a firstopening portion among the opening portions with respect to thereflection portion.
 7. The liquid consuming apparatus according to claim1, wherein the plurality of liquid containers includes a first liquidcontainer and a second liquid container whose capacity is smaller thanthat of the first liquid container, and the reflection portion of theholder is provided in the holder on the side of the second liquidcontainer.
 8. The liquid consuming apparatus according to claim 1,wherein the second direction is a direction orthogonal to the firstdirection.